Few electrical problems on my 2006 western star 4900ex

First is my right turn trailer circuit is getting low voltage back to the lights. My trailer had a bad spot in the harness. Some wires got melted together. I think it damaged something in the trucks circuit. I get turn signals on the tractor correctly. On the trailer I get left turn , but right turn is very dim, only showing about 5 volts making it to the back. Is there some sort of replaceable flasher relay I can change. The truck has a signal Stat 900 turn signal switch.
Second issue is a/c compressor won't disengage, unless I unplug it. Have also tried unplugging the high pressure switch. Also tried removing the high pressure switch and pluging it back in. I also believe this problem is causing my engine fan to stay on, as it won't disengage either.

 

Unfortunately it doesn't matter what position the switch is in. Although that is a point I had not considered. The vents do change with the switch. I was hoping someone else had solved this problem. I may have to start disconnecting all the wiring in the AC system one by one

 

I do have one of those. Although I have been a little disappointed with it. Those male prongs loosened up on mine resulting in me losing one of the prongs

 

I do have a dash switch for the engine fan. The pressure switch is a 4 prong. It was recently replaced. No change. Unplugging it

 

Unplugging it made no change. I plugged the old switch back into, but not screwed onto the drier. No change